Propeller mounting



July 6, 1948.

PROPELLER MOUNTING Filed May 11, 1945 4 Sheets-Sheet 1 gwuc/wbo o fiber as R. E. SHARPES 2,44 9

July 6, 1948. E, A PES J 2,444,539

PROPELLER MOUNTING Filed May 11, 1943 4 Sheets-Sheet 2 July e, 1948. V E, HARPE 2,444,539

PROPELLER MOUNTING Filed May 11, 1943 4 Sheets-Sheet 3 July 6, 1948. s s 2,444,539

PROPELLER MOUNTING Filed May 11, 1943 4 Sheets-Sheet 4 56' I a2 a; A:

Patented July 6, 1948 UNITED STATES 2,444,539 PROPELLElti/IOU'NTING Roy E. Sharpes, Harrisonburg, Va. Application May 11, 1943, Serial No. 486,587

pitch, the position and consequent pitch of the blades at any time being a function of the resultant effect of these two opposing forces.

One of the objects of the invention is to provide an integral hub construction including stub shafts constituting the axis of swing of the blades either radially disposed or offset with respect to the axis of the drive shaft. 4

Another object of the invention is to provide a blade, the base or root end of which is provided with a housing either integral or attached, forming a journal about the hub stub s'hafts, with interposed bearings and adequate provisions resisting the centrifugal thrust.

A further object of the invention is to provide a propeller blade construction as described, in which the pitch equalizer mechanism or apart thereof is carried by the housing.

Still another object of the invention isto provide a'sectional propeller blade, the base or root section comprising a socketed member with a lateral opening into which the outer section or blade proper may be laterally inserted, with means for securing said outer section compressively in said socket.

Other objects of the invention will appear as the following description of preferred and practical embodiments thereof proceeds.

In the drawings which accompany and form a part of the following specification, and throughout the several figures'of which the same characters of reference have been used to denote identical parts:

Figure 1 is a front elevational view of a propeller embodying the principles of the subject invention, the outer portions of the blade being broken away; 4

Figure 2 is a side elevation;

Figure 3 is a vertical cross-section through the OFFICE ATENT hub and adjacent portions of the propeller blades;

Figure 4 is a cross-section taken along the I line 4-4 of Figure 1;

Figures 5 and 6 are side views in elevation showing respective positions of the propeller blades, Figure 5 showing the position induced by centrifugal force in which th blades are in the plane of rotation of the propeller and the pitch at a maximum, and Figure 6 showing the blades under theinfluence of the forward air thrust, in which position the pitch is at a mini mum; I

Figure 7 illustrates a slight modification of l the hub shown in Figure 3, in which the stub shafts are offset on opposite sides of 9. diametrical plane through the axis of the drive shaft;

Figure 8 shows a slightly modified form of the invention in which the blades, including the hous-" ing; are each an integral member;

Figures 9 and 10 illustrate, respectively, 'a front and side elevation of a modified form of the invention, the blade tips being omitted;

Figures 11 and 12 illustrate a furthermodification of the invention, Figure 11 being a side elevation, and Figure 12 being a front view partly in'section.

Referring now in detail to the several figures, and first adverting to that form of the invention illustrated in Figures 1 to 4, the numeral i represents the drive shaft which rotates in the direction of the arrow shown in Figure 1. A hub 2 is suitably fixed to the drive shaft, said hub being formed with the integral stub shafts 3 and 4. In the illustrated form of the invention the stub shafts extend in diametrically opposite directions with their axes in a line perpendicularly intersecting the axis of the drive shaft. As shown, the base portions 5 and 6 of said stub shafts are of larger diameter than the outer portions pro-' viding shoulders I and 8 which afford a seat in the bearings 9.

Each blade is provided with a root member or socket I 0 which includes a housing ll adapted to be journaled about the stub shaft 3 and the axis of which housing forms an acute angle with the median longitudinal axis of the blade. Thehousing ll preferably has an interior collar l2v forming an inner shoulder l3 adapted to rest upon the bearing 9, and an outer shoulder l4 afi'ording a seat for the lowermost of a column of bearings I5, I6 and IT. The number of bearings in said column may be optional. Said bearings closely surround the stub shaft. The outer end of the stub shaft 3, as shown, is threaded and receives a castellated nut l8 seated upon a washer is which rests upon the uppermost bearing. The nut I8 is suitably locked by a cotterpin 19' or other locking device. The centrifugal thrust of the rotating blade is transmitted through the collar I2 of the housing ll against the stack of bearings I5, IE and I1, being resisted by the nut l8 and washer I9. To retain oil or grease in the bearings, the housing is preferably closed by a cap 20. The construction as above described is duplicated for each of the blades and stub shafts.

Pitch equalizing mechanism is provided comprising a fitting 2i fixed at the inner end of each housing, comprising gear segments 22 and 23 on opposite sides which mesh with gears "24 "and2'5 journaled on pins 26 and 21, which asshow-n, are integral with the hub, the gears 24 and 25 being secured by nuts 2'! and-28 screwed on -to the ends of the pins 26 and 21, suitable washers 29 and 3|] intervening. The gears 24 and 25 are segmental,-as .indicated in Figure 2, recesses 58 beingforined betweenthe segments, one of which is employed in connection with a stop pin 59 fixed to thehub to establisha maximum and minimum limit to. the pitch adjustment of the propeller blades.

.In the illustrated embodiment of the invention, two blades are shown. It is to be understood by those skilled in the art that the number of blades is immaterial and that the angular displacement of -the stub shafts is dependent upon the number of blades.

=.'Inoperation, assuming that the motor 1 is climbing so that the load on the propeller-is at its maximum, the R. P- M. of the motor will be reduced so-that centrifugal force will diminish and the forward thrust of the air will swing the propeller'blades forwardly, reducing the diameter of the propeller. The pitch will also'be diminished, decreasing the-load and permitting the engineto speed up 'so that the power-oi the engine will be -correspondingl-y increased. As the airplanelevels off and theload' eeorrespondingiy diminishes,-centrifugal force will act to draw thebla'des *backtowards a 'plane perpendicular to the drive shaft of the propeller, increasing the diameter of the propeller and increasingthe pitch of -.the :blad-es. This will tend to reduce the R. P: M. of the motor and reduceitspower-outprutiacoordin'gly. Thusythe pitch changes automatically 'according to the load, and the R. P. M. of the engine for'any given throttle-opening is maintained substantially constant.

Referring-toFigure'I, a slightly modified form of "hub construction is shown, in which the stub shafts 333.1111 4 .are offset from the hub Z on opposite sides of a plane p-assingthrough the axis orthe'hub. 'This arrangement has the advantage that-the median longitudinal axes of the blades-pass more nearly through'the axis ofthe drive shaft, giving a better balance of thestresses to which the propeller is-subjected.

Referring againto Figures 1 to 4, inclusive, the socket member i'll is open laterally on the side adjacent the leading edge,'the line of opening being indicated at 3'! in Figure 3. The interior of the socket member is wedge-shaped toward the trailing-edge, as shownat 32 in Figure 4. Thechamber within the socket member is narrower adjacent the upper end 33 thereof, than at the base. The blade proper :34 of the propeller is insertable laterally through the opening 3|, and is shaped to conform to the contour of the socket chamber. It is wedge-shaped toward the trailing edge, as shown at 35 in Figure 4, and wider at its lower end than in the zone of the top of the socket member It in a plane perpendicular to the view shown in Figure 3.

Furthermore, the interior of the socket member I9 is provided with the parallel tapered ridges 36 and the root of the propeller .blade proper is formed with corresponding grooves 31. In mounting the propeller blade 34 within the socket member w, it is pushed in laterally through the opening 3|,the. grooves 3.! riding upon the ridges 36, until the wedge-shaped portion 35 snugly fits F the wedge-shaped portion 32 of the socket chamber. The propeller blade 34 cannot become displaced in an endwise direction because of the interdigitationof the ridges 36 and grooves 31,

and in View of the fact that the lower end of the propeller is wider than the opening through theupper end of the socket member. When the blade 34 is thus in position to be tightened, the

opening 3| isclosed by a cap 38. .The meeting edges of the socket member Ill and the .cap 38am formed with lapping flanges 39 slidable in inside andioutside rabbe'ts on therespective cap and socket member. The ends of saidiflanges are spaced from the ends of the respective rabbets when the cap is first placed in position, andare drawn together in the operation oftightening the ap .andcompressively securing the propelleriblade 64. The outerfaceof theoap is formed wltha recessidll, the bottom. of which has. the form of two plani-form surfaces 4] and 42 intersecting at an obtuseangle. .Pairsof outwardly-divergent bores 43 and M are formed through the cap-in said planiformzsurfacesat spaced longitudinal intervals. The blade 34 :is tormed withdivergent bores 45 andflfi which register withtheboresM and 44 when'the cap is in place. Thesocket member is providedw-ith apertures-41 and- 48 registeringwiththewboresdfi and. The outercpposite faces .of the socketmemberlll are provided withcounterbores 4.9 and 50, registering with the bores and 4.8.. ,lncl-inedrheadedabolts 5| .and 52 pass through the registering boreslin the socket member .blade34 and: cap 38, the heads being seatedin the counterbores- 49 and 50. The .outer ends of the bolts 51 and 5,2 are threaded randreceive the skirted nuts-53 and-54, :the heads of which. nuts rest against theplaniform surfaces 4.! and-412 and-theskirts of "which are receivedin the bores-43 and 4.4. The last named.-bores-,-=as well as the bores. 45 audit in the propeller blade arelargerin diameter than the respective .nuts and bolts so as-to-permit movement of the .cap and propeller blade when the nuts are tightened. The inner surface ofthe-cap38 is made toconform to the shape of theadjacent surf-aceotthe root portion ofthe blade. Whenthe nuts "53 and-54 are tightened-the cap is forcedtowards the socket. member I'll; and in turn, forces the procor-respondsto the adjacent contour of the cap 38. The-plate'is secured by aseries of screws 56, which fasten into threaded sockets 51 formed in the longitudinal central portion of "the cap.

It is obvious that with the above construction the lateral thrust of the blade is always in the direction of the closed integral part of the socket member l0 and not against the cap, that the blade is rigidly and compressively held against the possibility of relative vibration between itself and the socket member and that it is impossible for the blade to be loosened or displaced through centrifugal force.

It is contemplated thatthe blade 34 may be made of metal, wood, plastic or any other eligible material.

Referring now to the modification of the invention shown in Figure 8, this differs from the form already described, in that the housing II and the entire propeller blade 60 are one integral member.

In that form of the invention illustrated in Figures 9 and 10, the housing Si is integrally formed with one of the matching members 62 of a socket 63 which embraces the root end of the propeller blade 64. The socket members 62 are provided adjacent their plane of separation with flanges 65, having registering bolt holes and being brought together in clamped relation to the root end of the propeller blade by means such as the nuts 65. The chamber of the socket 63 is larger at the bottom than at the top, and the root end of the propeller blade 64 is correspondingly shaped, whereby the propeller blade is restrained from displacement through centrifugal force.

The pitch equalizing mechanism in this form of the invention is constituted by the arms 61 and B8 integral with the respective housings 6|, or fixedly secured thereto, which extend inclinedly and at their ends carry the bearing pins 69 and ill, which pins intersect a common plane through the axis of the drive shaft. A pair of links H and 72 have eyes 13 and 14 at their outer ends journaled on said bearing pins and at their opposite ends the links H and 12 and yokes and i6 pivotally interconnected to one another and to a sleeve Ti, which slides along the fixed guide 18 coaxial with the drive shaft. As shown, the arms 61 and 68 are braced by the rods 19, rigidly secured to the housings BI and to said arms adjacent their free ends.

Referring now to that form of the invention shown in Figures 11 and 12, the gear type of equalizer previously described may have the objection that all meshed gears are subject to a certain amount of lost motion or backlash, the presence of which might defeat precise pitch equalization of the blades, resulting in vibration. The structure described in Figures 11 and 12 provides a pitch equalized in which lost motion is entirely absent.

The hub is furnished with axially aligned cylindrical bosses 80 and BI on opposite sides of the drive shaft and perpendicular to the turning axes of the propeller blades. Said bosses serve as journals for the identical rocking levers 82, each of which has diametrically opposed arms 83 and 84 terminating in ball ends 85. The rotatable housings 86 at the root of the propeller blades are each provided with a spherical head 81, and the balls 85 at each end of the rocking lever and the adjacent spherical heads 81 are connected by a link 83 having spherical seats 88' and 89 bearing against the respective ball ends and spherical heads. One of said seats is formed in a nut 90 screwing into one end of the link 88, by which means the links may be adjusted to draw snugly against the embraced ball end and spherical head, obviating any lost mo-' tion.

The arms 83 and 84 of the rocking lever 82 are formed with deep webs extending close to the surface of the hub and cooperating with stops 9| and 92 fixed to the hub which establish maximum and minimum pitch limits.

The equalizing mechanism is duplicated on both sides of the hub as shown whereby it iskept in tension and lost motion prevented.

It will be understood to those skilled in the art that I have produced a simplified and eflicient variable pitch propeller of the self-operating type, amply safeguarded against the disruptive and vibratory strains to which'a-propeller is inherently subjected, and that the details of construction and arrangement of parts are byway of example and not to be construed as limiting the scope of the invention as defined in the appended claims.

1. Propeller construction comprising a blade, a socket member for securing the root end of said blade, said socket member having a lateral opening on the leading side for the lateral introduction of the blade, and a cap for closing said opening engageable with said root end, the chamber of said socket member being wedge-shaped toward the trailing edge, the root end of said blade being shaped to fit said socket chamber, and bolts passing through said cap, blade and socket member for drawing said cap compressively against said blade and wedging the latter in said socket member.

2. Propeller blade construction comprising a blade, a socket member for securing the root end of said blade, said socket member having a lateral opening in the leading side for the lateral introduction of the blade, and a cap for closing said opening engageable with said root end, the chamber of said socket member being Wedge-shaped toward the trailing edge, the root end of said blade being shaped to fit said socket chamber, said cap having an external recess the bottom wall of which has convergent planiform surfaces, bolts passing through bores opening in said surfaces normal thereto extending through said cap, blade and the sides of said socket membar, the heads of said bolts being countersunk in said socket member, and nuts on said bolts thrusting against said planiform surfaces of said .cap recess for drawing said cap compressively against said blade and wedging the latter in said socket member.

3. Propeller blade construction as claimed in claim 2, including a plate closing said cap recess, secured to said cap.

4. Propeller blade construction as claimed in claim 2, said blade and socket member having transverse interdigitating grooves and ribs.

5. Propeller construction including a blade, comprising a socket member for securing the root end of said blade, said socket member having a hub connection at one end and a root end receiving chamber at the other, said chamber being wedge shaped toward the trailing end, the Wedge shaped portion of said chamber being defined by integral convergent walls which terminate in a plane extending transversely of said chamber, closer to the leading end than to the trailing end, and parallel to the neutral axis of said blade, said walls defining a lateral opening facing the leading end for the lateral introduction oi the root end of the blade, the latter being shaped to fit said socket chamber, a plate closing said opening engageable with said root end; and: means fordrawing said plate and socket member together against said root end whereby itis 'wedginglypressed against the convergent wallseof said chamber.

ROY E. SHARPES.

REFERENCES CITED The-following references are of record in the file of this patent:

, UNITED STATES PATENTS Number Name Date 11,455,442 Leparmentier May 15, 1923 1,638,695 Leitner Aug. 9, 1927 "1,834,350 Schroeder Dec. 1, 1931 1,834,351 Schroeder Dec. 1, 1931 21,851,874 Seppeler Mar. 29, 1932 Number Number 

